The Conditions For Life On Earth Flashcards
How long ago did earth form?
4.6 billion years ago
Why was mass important for for life?
Prevented most gases from escaping into space
Atmospheric pressure was high enough to prevent all liquid water from boiling
What are the essential elements for life?
Carbon
Hydrogen
Oxygen and nitrogen
How were the essential elements found on early earth?
Methan
Ammonia
Carbon dioxide
Why is water vital?
General physiological solvent in most biological reactions
Transport
Temperature regualtion
For aquatic/ early life
Why is distance from the sun important?
Produces temperatures suitable for life
Too close or far would mean there would be no liquid water
The time taken to produce night and day cycles was fast enough to reduce extreme temperatures
Why is the axis of rotation important?
The angle at which earth orbits the sun produces easonal variations
Why is speed of rotation important?
24hr period of rotation reduces temperature extremes
Why is magnetic field important?
Deflects solar winds and prevents biologically damaging radiation reaching earths surface
Why is solvent water important
General physiological solvent
Most chemical reactions in living organisms involve reactants dissolved in water.
Why is water important for transport in organisms
Water is the solvent in the blood and sap where it transports dissolved gases, sugars, amino acids, mineral nutrienst and waste products.
Why is water important for temperature control?
Evapouration of water abosorbs heat causing temperatures to decline
Why is it important that water anomalously expands on freezing
Water is most dense at 4*c so water that is cooler than this floats, stopping the convection currents that may have cooled the whole water body
Why is it imporant that water has a high heat capacity
Water warms and cools down slowly which helps to moderate the rate and size of temperature change
What aquatic habitats does water provide?
Rivers Oceans Seas Marshes Lakes Ponds
Why is it important that water absorbs UV
Protected living organisms in the oceans before the ozone layer developed which absorbed UV in the stratosphere
Why was temperature range important?
Most areas of earth have temperatures between 0-35*c so most areas are warm enough to have liquid water but not hot enough to denature proteins
Why is carbon dioxide important?
Photosynthesis
Synthesis of carbohydrates, proteins and lipids
Why is nitrogen important
Protein synthesis
Why is solar insolation important
Sunlight provides the energy for photosynthesis
Heat produced by sunlight drives the water cycle and warms the surface and oceans
Amount abosrbs depends on albedo
Composition of the atmosphere controls how much infrared is aborobed and converted to heat
What is the albedo of a surface?
It’s reflective power or lack there of
What are Archaea?
Photosynthetic algae
When did Archaea form?
2.7 billion years ago
Why are Archaea important?
Had the ability to photosynthesise and produce oxygen as waste.
How did oxygen get into the atmosphere?
Oxygen reacted with iron in the oceans until all reaactions had taken the place then a surplus of O2 was released into the atmopshere 2.45 billion years ago
Why was it important for oxygen to be in the atmopshere?
Aborobed UV light producing a dynamic equillibirum of reactions with O3, O2 and O
Important as made life on the surface possible
What was the period of oxygen period bulid up called?
Proterzoic ended 540million years ago
Why is carbon sequestration important?
Photosynthetic organims, photoautotrophs absorbed CO2 some of which is stored in geological sediments and fossil fuels
This help reduce long term temperature rise
How much brighter does the sun get every 1 billion years?
10%
Why are biogeochemical cycles important?
Meant relatively small amounts of some nutrient elemnts could support life over long periods of time without resources being depleted
Why was tranpiration important?
Transpiration returned water vapour to the atmosphere and increased rainfall in other areas making more plant growth possible
What can a radioisotope composition be used for
Used to date samples such as the ratio of carbo-12 to carbon-14
Oxygen-18 to oxygen-16 used to estimate past temperatures
Compostion of past atmopshere analysed from bubbes in ice cores
